Pulverized fuel burning gas heater



March 23, 1948. R. RUEGG 2,438,416

7 PULVERIZED FUEL BURNING GAS HEATER Filed July 5, 1944 I5 1 5 -l i 3 1 2 4 1 L 1 E K L 12 5 8Q- Quuwnkoz RudOI'F Ruegg Patented Mar. 23, 1948 rULvamzun FUEL BURNING ens HEATER Rudolf Ruegg, Zurich, Switzerland, assignor to Aktienge'sellschaft Fuer Technische Studien, Zurich, Switzerland, a corporation of Switzerland Application July 3. 1944, Serial No. 543,229 In Switzerland July 21, 1943 1 Claim. 1

This invention relates to a gas heater intended more especially for thermal power plants, in which at least the greater part of a gaseous working medium, preferably air. describes a circuit and has to be heated by a supply of heat from an external source. The object of the invention is to ensure the greatest possible reliabilit in operation and at the same time a good efliciency of the gas heater, .For this purpose in a gas heater according to the present invention a part of the working medium to be heated effects cooling of at least one section of the heater where the stresses are particularly severe, said part flowing in parallel with the remaining main part of the working medium.

A preferred embodiment of the invention is illustrated by way of example and in a simplified gas flue 3 arranged, when looking in the direction of flow of the combustion gases, beyond the mode of representation in the accompanying.

drawing, in which the single figure shows a gas heater with slag collecting receptacle, in which heater a part of the work medium to be heated eflects cooling of the bottom of the slag'collecting receptacle and other parts eflect cooling of the ceiling and at least one side wall of the combustion chamber,

In the drawing the numeral i denotes the combustion chamber of an air heater A of a thermal power plant in which air describes a cycle and has to beheated by a supply of heat from an external source. The air heated in said heater A passes through a pipe 8 into a turbine 3| where it expands whilst giving up energy to a machine 32 which, for example, can take the form of an electric generator. The turbine 3| simultanenusly drives a turbo-compressor 33. The expanded working medium issuing from the turbine 3| passes through a pipe 34 into a heat exchanger 35 of the counter-current type, where it gives up heat to the working medium that has been compressed by the compressor 33 and which flows through a pipe 36 from compressor 33 to this tubular heat exchanger 35. After having given up heat in the heat exchanger 35 the expanded working medium passes through a pipe 31 and a cooler 38 into the compressor 33, whilst the working medium of higher pressure which has taken up heat in the heat exchanger 35, passes through 'a pipe 5 into the heater A. The

. lower section of the combustion chamber l of this heater A is designed as a slag collecting receptacle 2. The reference I designates a burner supplied with pulverized fuel, and so related to the receptacle 2 that slag in the receptacle will be kept in a molten state so that it may be tapped oi! as circumstances mayrequire. In a waste combustion chamber l a tubular heating system 4 is installed. The air to be heated is supplied to this system 4 through the above mentioned pipe 5, a part of said air passing at point 6, which is situated. when looking in the direction of flow of the air, in front of the system 4, into a pipe 9. The greater part of the air supplied through pipe 5 passes, however, into the heating system 4 and then into a tubular heating system I, which is arranged in the combustion chamber I in such a manner that the lower part of the tubes of this system I is disposed between the slag receptacle 2 and the inside face of the combustion chamber I. The lower part of the system I is thus protected against excessive losses of heat towards the exterior. The air which has been brought to the required final temperature in the heatingsystem 1 flows through pipe 8 into the turbine 3i. The part of working medium which branches oil at point 8 passes through pipe 9 into a system of tubes l0 located underneath the bottom of the slag receptacle 2, so that the air flowing through this system of tubes Ill effects cooling of the bottom of the slag receptacle. Since in doing so this air takes up heat, its temperature is raised simultaneously. The part or working medium heated in this manner passes into a pipe II and finally again mixes with the main current of working medium at p int 12. The two currents of working medium to be heated in the heater A thus flow parallel to one another.

At a. point l3 on the pipe 5, a, pipe I4 is branched on and leads to a tubular system I5 which efiects cooling of the ceiling of the combustion chamber I. The medium heated in the system i5 returns to the main current of working medium at [6. It will be observed that the gaseous medium to be heated is heated on the once-through basis, and that the medium which does the protective cooling is not heated in the main portion 4 of the heater or any part thereof.

the flow ot the medium to be heated; a pipe con- I nected to said second heating system for carrying ofl the medium heated in said two heating systems: a heat exchanger connected to said supply pipe at a point upstream as to said first mentioned heating system and to said pipe for 10 carrying oil. the heating medium at a point which is, when considered with reference to flow oi said medium. beyond said second heating system and located to derive heat chiefly from and exercising a protective cooling eflect upon the slag collecting receptacle; and a second surface heat exchanger located to derive heat directly from theceiling of said combustion chamber and connected both REFERENCES CITE!) The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 982,449 Timmins Jan. 24, 1911 1,986,951 Vogel Jan. 8, 1935 2,119,817 Keller July 7, 1938 2,166,199 Shoemaker July 18,1939 2,174,663 Keller Oct. 3, 1939 2,224,544 Keller Dec, 10, 1940 2,380,169 Gygi July 10, 1945 

